# United States Army, Japan

United States Army, Japan (USARJ) is a Major Command of the United States Army. It operates port facilities and a series of logistics installations throughout Honshū and Okinawa. USARJ participates actively with the Japan Ground Self-Defense Force in bilateral training exercises and the development of bilateral plans. It commands and supports United States Army assigned units, attached units, and augmentation forces and employs these forces in support of the commander. USARJ maintains and strengthens the credibility of deterrent power in the Pacific through maintenance of defense facilities, war reserves and operational project stocks. USARJ is headquartered at Camp Zama.
As the Army Component Command to United States Forces Japan (USFJ) and as a Major Subordinate Command of United States Army Pacific (USARPAC), United States Army Japan (USARJ)/I Corps (Forward) is responsible for providing support of Article V (Defense of Japan) and VI (ensuring regional stability) of the U.S.-Japan Mutual Security Treaty.
It serves as a forward stationed Army headquarters. It supports regional security cooperation activities with the Japan Ground Self Defense Force, contributing to the security of Japan and the maintenance of peace and security in the Far East, and provides communities of excellence and installation operations that support Soldiers, Civilians, and their Families.

## Units

The following units make up US Army Japan:
* United States Army Japan, Honshu, Japan
** I Corps (Forward)
** U.S. Army Garrison Japan (Camp Zama)
*** United States Army Aviation Battalion, Japan
*** 35th Combat Sustainment Support Battalion
**** 623rd Movement Control Team
*** 78th Signal Battalion
*** 311th Military Intelligence Battalion
*** United States Army Japan Band
*** 836th Transportation Battalion
*** Ammunition Depot, 10th Support (Group Regional)
*** 10th Missile Defense Battery (TPY-2 Radar)
*** 14th Missile Defense Battery (TPY-2 Radar)
*** 88th Military Police Detachment
*** 901st Military Police Detachment
*** 403rd Army Field Support Brigade Northeast Asia (NEA) Battalion
*** 403rd Army Field Support Brigade Logistics Readiness Center (LRC)
*** 38th Air Defense Artillery Brigade
** U.S. Army Garrison Okinawa (Torii Station)
*** 10th Support (Group Regional) (Brigade-level logistics)
*** 1st Battalion, 1st Air Defense Artillery Regiment (Patriot)
*** 1st Battalion, 1st Special Forces Group
*** 247th Military Police Detachment
*** 835th Transportation Battalion
*** 505th Quartermaster Battalion
*** 78th Signal Battalion
** JAPAN ENGINEER DISTRICT U.S. Army Corps of Engineers
** Brigadier General Crawford F. Sams United States Army Health Clinic Japan
** DENTAC-J
** Public Health Activity - Japan

## History

The earliest origins of United States Army Japan can be traced to General Douglas MacArthur's assumption of command of U.S. Army Forces in the Far East. In July 1941, USAFFE was established in Manila. The command was destroyed as the U.S. were defeated in the Japanese invasion of the Philippines. After the end of the Second World War, the Army Forces Far East title was resurrected as the land forces element of the Far East Command in Tokyo. When Far East Command was disestablished in 1957, several smaller U.S. Army commands were created.
U.S. Army Japan (USARJ) first appeared on 1 July 1957 as a major subordinate command of United States Army Pacific (USARPAC) in Hawaii. Reorganized in September 1968, USARJ employed a new structure to maximize operational efficiency, while keeping its existing missions and functions.
In May 1972, the reversion of Okinawa to Japanese control resulted in the realignment of the Army's Pacific commands, with HQ USARJ absorbing elements for Okinawa, adjusting the command chain. IX Corps was transferred from Okinawa, and collocated with this command, to become HQ USARJ/IX Corps.
In July 1974, a USARJ reorganization established three subordinate commands: U.S. Army Garrison, Honshu (USAGH); U.S. Army Garrison, Okinawa (USAGO); and the U.S. Army Medical Department Activity-Japan, (MEDDAC-JAPAN).
In January 1975, with the discontinuance of USARPAC, USARJ was designated a major Army command, reporting directly to the Department of the Army.
In August 1990, USARPAC was reestablished. USARJ became a major subordinate command of that headquarters, as well as continuing as the Army Component Command of U.S. Forces, Japan (USFJ). In 1994, IX Corps was replaced by 9th Theater Army Area Command. In November 1999, it was redesignated the 9th Theater Support Command (TSC). There were several minor reorganizations and redesignations over the next decade, so that by September 2001, USARJ consisted of logistics bases in Japan and Okinawa.
In September 2007, the 9th TSC was inactivated. In December 2007, I Corps (Forward) was activated in Japan in line with the Army's transformation efforts. USARJ remains headquartered at Camp Zama, where it engages in numerous bilateral activities with the Japan Ground Self-Defense Force (JGSDF), and performs duties as United States Forces Japan's Army Component Command.
Command of the 78th Signal Battalion remained with the Hawaii-based 516th Signal Brigade (formerly 1106th) and operational control remains with the commander, USARJ/9th TAAC and since December 2007, USARJ/I Corps (Forward).
On 11 March 2011, a devastating magnitude 9.0 earthquake and tsunami struck the northeast coast of Japan. Within minutes, USARJ began humanitarian assistance and disaster relief operations in support of the JGSDF during Operation Tomodachi, Japan's largest-ever bilateral operation. USARJ supported the affected people after operations officially ended, by providing equipment and maintenance support to the JGSDF until September.